SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '2b3cc8b43c4fa02ff073455d12db07d63b67b80e3d7047c9bdfb84de2cd0080c' 
  AND token = 'U1KuuWNTuHQCuVdlXZAF4kkiEFeMqLPCMqnclrOjXIU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}